Apparatus for graphically ascertaining the stability and trim of ships under assumed loads



s. B. RALSTON. A

APPARATUS FOR GRAP HICALLY ASCERTIUNING THE STABILITY AND TR IM 0F SHIPSA UNDER ASSUMED LOADS. v APPLIQATIUN men MAR- 11, 1920. 1,426,103.Patented Aug. 15, 1922.

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s. B. RALSITON.

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UNITED sra'rss rasr orrics.

SHIRLEY BROOKS RALST ON, O13 GLASGOW, SCOTLAND.

APPARATUS FOR GRAPHICALLY ASCER'I'AI-NING THESTABILITY UNDER ASSUMEDLOADS.

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AND TRIM OF'SI-IIPS Specification of Letters Patent. Patented A11g';15,1922.

Application filed. March 11, 1920. Serial No. 364,983.

To all whom it may concern: r

Be it known that l, SHIRLEY Bnoous Help s'roN, a subject of the King ofGreat Britai residing at ltosyth, Glenburn Bead, Bears (lGlL'iililSQ'OW,Scotland, have invented new and useful Improvements in Apparatus forGraphically i iscertaining the Stability and Trim of Ships Under AssumedLoads, of which the following is a specification.

My invention relates to improvements n apparatus of the kind describedin the specification of my former Brltish Patent No.

1156i of 191.0 for graphically ascertaining the stability and trim ofships under assumed loads. H l

Apparatus as described in my aforesaid :lormcr specification comprises atablebearing' a longitudinal profile diagram of the ship in re. poet ofwhich the calculations are to be made and designed to be supportedalternately on longitudinal and transverse horizontal pivots, incombination with a counter-balancing; platform or slide of known weightdesigned to be moved longitudinally on the table and furnished with aweighted counter-balancing arm movable transversely upon it.

The platform is marked with a deadweight scale plan and a G. M. ormetacentrie heiu'ht scale and the counter balancing arm is inarked witha G. M. scale corresponding with that upon the platform. Loose weightsrepresenting cargo or other load are also provided for use on the table.

Whilst the apparatus constructed above described gives good results inpracticeyet a certain inconvenience is experienced in its manipulationowing' to the fact that an appreciable area of the diagram is obscuredby the platform.

The object of the present invention is to obviate this disadvantage andto this end I dispense with the longitudinally movable platform andsubstitute therefor a parrot weights adapted to be adjusted in positlonrespectively along the transverse and longitudinal edge or rim of thetable. For example, the movable weights may be caused to move by rackand pinion over transverse and longitudinal scales provided upon thetable.

In conjunction with the table and movable weights there is also provideda board having marked upon it deadweight and justed in position in anyconvenient way,

say byracks and pinions.

To enable the invention to be fully understood I will describe it byreference to the accompanying drawings, in which 2 Figure 1 is a planview of the apparatus made according to the invention.

t Figure 2 is asection on the line ure 1. V

Figure 3 is a section on the line 3 -3 Fig ure 1. r I

Figure-4 is a plan view of the scale board.

I Figure is a section on the line 5-5 Fi ure 4, and 1 I Figure 6 is asection on the line 66 Figure 4-. I

Referring first to liigures 1 to 3, a indicates 22 Fig- ,the table whichhas marked upon it the longitudinal profile diagram 5 of the ship inrespect of which the calculations are to be made. As described in thespecification of my former patent aforesaid, c, 0 and (Z, (Z are theknife edged trunnions by means of which the said table a can be mountedupon suitablesupports (not shown) so as to turn on transverse andlongitudinal axes, re spectively. e and f are the two weights which aredesigned to be traversed along the transverse and longitudinalupstanding rims or edges (L1 of the table, respectively,

this being effected, in the construction illustrated in the drawing, bymeans of the racks g, provided on the inside faces of the said rims, andpinions l2, gearing with the said racks and carried by upright pins 71mounted in bearings j in the sliding weights (2 and f and furnished withmilled heads k by means of which they can be turned. Z

01-, Figures t, 5 and 6, represents the scale board, which has markedupon it the dead weight and draft scales 0 and p and also G. M. curvesand trim curves 9'. The board is also iitted with the scale bar 8 whichextends longitudinally across the said board, and is moved transverselythereof through the medium of the racks t and pinions u and which bar ismarked with the (i. M. scale n and the trim scale '20..

The apparatus is used as follows, that is to say. the loose weights areplaced upon the profile diagram on the table in the proper positions torepresent the assumed load or deadweight and. to acertain the stabilityof the ship, the table is supported. upon the transverse pivots cl andthe G. M. weight a adjusted in position until the table balances in thehorizontal plane. The figure on the scale or register Z indicating theposition of the G. M. weight is then noted and the G. M. scale bar 3adjusted on the szale board it until it coincides with the indication onthe scale 0 of the assumed load. The point at which the G. M. scale ofthe bar 8 is intersected by the G. M. curve bearing the figure obtainedby the adjustment of the-G. M. weight on the table a gives the G. M.required.

A similar manipulation of the longitudinal weight 7 and pivots 0 enablesthe trim to be ascertained.

Claims 1. An apparatus for graphically ascertaining the stability andtrim of ships under assumed loads comprising a (.liagran'l table,supporting means arranged along the longitudinal and transverse edges ofsaid table. weights movably mounted upon said supporting means and meansfor sliding said weights thereon.

2. In a1 )paratus of the kind herein described the combination with adiagram table having graduated longitudinal and trans verse edges, ofracks and pinions mounted along said respective edges. and a pair ofweights adapted to be traversed through the medium of said. racks andpilllOikE. along said longitudinal and transverse edges respectively.

3. ll 'iparatus ot the kind herein referred to comprising a tableprovided with a longitudinal profile diagram of a ship and having itslongitudinal and transverse edges marked with the trim and G. M. scales,su iporting means arranged along said longitudinal and transverse edgesand a pair of weights slidable thereon and adapted to be adjusted inposition alon said scales.

SHIIUTEY BROOKS RALS'lOI l.

